Connective Tissue Flashcards
Name the germ layers in the embryo
Endoderm, Mesoderm, Ectoderm
What does mesenchymal tissue do?
Mesenchymal tissue creaes adult connective tissue like blood, supportive and proper tissues
What is adipose tissue dervied from?
The mesoderm, this separates brown and white fat
Where is connective tissue derived from?
Mainly the mesoderm
What is the main function of connective tissue?
Structural support
What functions does connective tissue provide?
Structural support, cushioning, delivery and storage of nutrients, cell repair
What is a fixed (resident) cell?
A cell that does not move from the tissue in which it originates
What is a non-resident cell?
A cell that is transient between tissues
What is connective tissue made of?
Cells (fixed or mobile), fibers, and ground substance
How does connective tissue differ from epithelial cells?
Connective tissue does not have a basement membrane
Name fixed cells
Fibroblast, Macrophage, Mast cell, Percyte, Adipocyte, Mesenchymal cell
Name mobile cells
Macrophage, plasma cell, lymphocyte, polymorphonuclear cells (neutrophils), eosinophil, basophils
What does the bone marrow make?
multipotent stem cells that evolve in to immune cells (eosinophil, neutrophil, plasma, lymphocyte, macrophage, osteoclast, red blood cell)
What does the mesenchymal cell make?
embryonic connective tissues including osteoblasts, adipocytes, and fibrolbasts
Name typical peripheral blood cells
Erythrocyte, lymphocyte, neutrophil, eosinophil, basophil, monocyte, platelets
Describe a fibroblast
Produce collagen and elastin, oblong heterochromatic nucleus with no visible cytoplasm
What cell is a macrophage derived from?
Monocyte
What is the main function of macrophages?
Engulfing antigen and presenting the antigen for T cells. T cells are activated to either cytotoxic CD4 T cells or helper CD8 T cells
Where are dendritic cells found
Dendritic cells have tree-like structures and are found in the skin and epithelium.
What is the function of dendritic cells
Present antigen to stimulate B or T cells at lymph nodes. Dendritic cells have a euchromatic nuclei and large cytoplasm
Where are mast cells located
Connective tissue. Mast cells produce heparin and histamine
What is heparin
Anti coagulant
Describe mast cell
Red granulated cytoplasm with large, dark nucleus
Mast cells account for allergic responses and wound repair
What is a pericyte
Contractile cell located on the edge of vasculature. Dark nucleus with little cytoplasm
Describe the mononuclear phagocyte system
Bone marrow makes a pluripotential stem cell, which matures to a committed stem cell to monoblast to promonocyte to monocyte that is secreted to peripheral blood. Monocyte becomes macrophage
Describe a lymphocyte
Dark, round nucleus with no cytoplasm
Describe a plasma cell
A mixture of heterochromatin and euchromatin in the nucleus to give a spotted look, basophilic cytoplasm and large golgi apparatus
How are antibodies produced
B-cells digest the antigen and presents antigen on cell surface. B cell interacts with activated T cells, differentiates in to a plasma cell and begins producing antibodies
Name types of lymphocytes
CD4+ T cells, CD8 B cells, Helper T cells, Natural Killer T cells, regulatory T cells
Describe a neutrohpil
Multi-lobed with fine, eosinophilic granulated cytoplasm. Granules contain proteases and respond to infections and wounds by phagocytosis. Neutrophils can cause vasodilation and account for half of the white blood cells
Describe eosinophils
Eosinophils are bi-lobed with red granules in the cytoplasm. Eosinophils respond to parsitic infections and produce peroxidase
Describe basophils
Basophils release histamine for allergic reactions are are rare
What are the longest and shortest cell life spans?
Lymphocyte (several weeks)
Basophils (2-3 days)
How many more white blood cells does the dog have compared to the human
Twice as many (8k vs 17k)
What is uncommon to see in the peripheral blood?
Neutrophil precursors: myelocytes and myeloblasts
What do precursor cells in the peripheral blood signal?
A large loss of blood, parasites, cancer
What are band cells?
Neutrophil. Band cells in peripheral blood may indicate illness
What are segmented cells?
Neutrophil. Segmented cells may indicate cancer or suppressed immune system
What fibers make the extracellular matrix?
Collagen and elastin
What is the most abundant protein in the human body
Collagen. Collagen is found in most supporting tissues
Describe Type I collagen
Produced in fibroblasts, most common. Found in fibrous supporting tissues (dermis, tendons, ligaments)
Describe Type II collagen
Found in hyaline cartilage and elastic cartlage, and is made of fine fibrils that disperse in the ground substance
Describe Type III collagen
Made of very fine reticular fibers (reticulin). Reticulin forms a mesh network for the liver, bone marrow and lymphoid organs
Describe Type IV collagen
Does not have fibrils but forms a meshwork with myofibrils for basement membranes
Describe Type VII collagen
Forms fibrils that anchor to the basement membrane
Describe elastin
Synthesized by fibroblasts, allows stretching and recoil. Present in skin, lung, blood vessels
What is the difference between collagen and elastin
Elastin stains brighter pink (darker) than collagen and is wavy. Elastin is stretchable, and disorganized while relaxed and organized while stretched. Elastin is present in arteries and appears shiny in the microscope
What is the ground substance?
The ground substance fills spaces between cells and fibers and provides a physical barrier. It is made from glycosaminoglycans (GAG) that are negatively charged and hydrophilic
What is the most common GAG?
Hyaluronic acid. Hyaluronic acid is not sulfated like most GAGs and is a very large molecule
Name other GAGs present in ground substance
Fibronectin, Chondronectin, Laminin. Interstitial fluid is present in ground substance
Why is cartilage resilient and compressible?
Proteoglycan aggregates repel each other
What stem cells are found in adults?
Pericytes (blood vessel) and satellite cells
What stem cells are found in infants?
Mesenchymal cells
Types of connective tissue
Loose irregular, Dense irregular, Dense regular
Describe loose irregular tissue
The most common connective tissue. Contains many resident and mobile cells, and consists of collagen and elastin. The fiber arrangement is loose and random to allow flexibility. Found in superficial fascia and lamina of the gut
Describe Dense irregular tissue
Densely packed, randomly arranged fibers. The skin and organ capsules have dense irregular
Dense regular
Made mostly of Type I collagen that are packed tightly and arranged in parallel manner. Fibrocytes (mature fibroblasts) are flattened between thick collagen fibers
What are made from dense regular tissue
Tendons, ligaments, aponeuroses. These structures have poor blood and nerve supplies and look smoother than muscle fibers
Describe dense regular elastic tissue
Dense elastic tissue is not common. It is densely packed, parallel elastin. Present in the aorta
What makes adipose tissue?
Adipocytes (single, clusters or masses of adipocytes)
How to differentiate an adipocyte
Basal lamina (CT does not have basal lamina)
Describe brown fat
Big nuclei, many mitochondria, stains darker than white fat and is multilocular which binds many oil droplets together
Compare brown fat vs white fat
Brown fat has higher energy than white fat, brown fat stores glycogen and is found in muscles, brown fat has many capillaries
What has the highest concentration of brown fat?
Infants and people who live in colder climates
